Magnetic sensor having second antiferromagnetic layers and two types of electrode layers on free magnetic layer and manufacturing method thereof

ABSTRACT

First electrode layers are formed on second antiferromagnetic layers, and in a step separate from the above, second electrode layers are formed above internal end surfaces of the second antiferromagnetic layers and the first electrode layers and parts of the upper surface of the multilayer film with an additional film provided therebetween. Since the first and the second electrode layers are formed separately, it is not necessary to perform mask alignment twice, and hence an overlap structure can be precisely formed in which the thickness of the second electrode layer at the left side is equivalent to that at the right side.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to magnetic sensors in which electrodelayers are formed to overlap a multilayer film, and more particularly,relates to a magnetic sensor in which overlap electrode layers at theleft and right sides can be precisely formed so that the filmthicknesses thereof are equivalent to each other.

2. Description of the Related Art

FIG. 21 is a partly cross-sectional view of a related magnetic sensor(spin-valve type thin-film element) viewed from an opposing face sideopposing a recording medium.

Reference numeral 1 indicates a first antiferromagnetic layer composedof a PtMn alloy or the like, and on this first antiferromagnetic layer1, a fixed magnetic layer 2 formed of a NiFe alloy or the like, anonmagnetic material layer 3 formed of Cu or the like, and a freemagnetic layer 4 formed of a NiFe alloy or the like are provided to forma laminate structure.

As shown in FIG. 21, on the free magnetic layer 4, secondantiferromagnetic layers 5 with a track width Tw provided therebetweenin the track width direction (X direction in the figure) are formed, andon these second antiferromagnetic layers 5, electrode layers 6 areprovided.

In the embodiment shown in FIG. 21, exchange coupling magnetic fieldsare generated in regions in which the second antiferromagnetic layers 5are provided on the free magnetic layer 4, the magnetizations of thefree magnetic layer 4 in the regions described above are fixed in the Xdirection shown in the figure, and the free magnetic layer 4 in thetrack width Tw is put in a weak single domain state so that themagnetization reverse may occur with respect to an external magneticfield.

In the related example shown in FIG. 21, there have been the followingtwo problems. The first problem is that element resistance cannot besatisfactory decreased. The reason for this is that the secondantiferromagnetic layer 5 is formed of a material such as a PtMn alloyhaving a high resistivity, and that sense current flows from theelectrode layer 6 to the free magnetic layer 4 side through this secondantiferromagnetic layer 5 (the flow of the sense current is shown by thearrows). The PtMn alloy mentioned above has a resistivity of anapproximately 170 μΩ·cm or more, and on the other hand, the electrodelayer 6 is formed of a material such as Au having a very low resistivityof approximately 2 to 6 μΩ·cm. Hence, even when a material having a lowresistivity is used for the electrode layer 6, according to thestructure of the magnetic sensor shown in FIG. 21, the sense currentmust flow once through the second antiferromagnetic layer 5 having ahigh resistivity, and as a result, decrease in element resistance cannotbe achieved. In addition, since the element height has been decreasedconcomitant with recent trend toward higher recoding density, theelement resistance is also increased.

The second problem is side reading. As described above, since flowingtoward the free magnetic layer 4 side through the secondantiferromagnetic layer 5, the sense current spreads wider than thetrack width Tw and then flows toward the free magnetic layer 4 side. Inthis step, since the magnetization of the free magnetic layer 4 in thevicinity of the track width Tw is not tightly fixed with the secondantiferromagnetic layer 5 and varies to some extent with respect to anexternal magnetic field, a so-called effective track width tends to belarger than the track width Tw (this track width Tw is also referred toas “optical track width” in some cases) shown in the figure.Consequently, the side reading is liable to occur in that externalsignals are read at positions apart from the track width Tw.

In order to solve the above two problems, the structure in which theelectrode layers 6 overlaps the free magnetic layer 4 in the track widthTw has been researched.

FIGS. 22 and 24 are views showing steps of manufacturing a magneticsensor in which electrode layers form an overlap structure. The viewsshowing the manufacturing steps, described above, are partlycross-sectional views each showing a magnetic sensor in themanufacturing step when viewed from an opposing face side opposing arecording medium.

In the step shown in FIG. 22, the first antiferromagnetic layer 1, thefixed magnetic layer 2, the nonmagnetic material layer 3, and the freemagnetic layer 4 are formed in that order from the bottom, and inaddition, on the free magnetic layer 4, the second antiferromagneticlayers 5 are formed with a predetermined space T1 provided therebetweenin the track width direction (X direction in the figure). For theformation of the second antiferromagnetic layers 5, as shown in FIG. 22,for example, a solid second antiferromagnetic film 5 is first formedover the entire surface of the free magnetic layer 4, resist layers 8with a predetermined space therebetween in the track width direction areformed on the solid second antiferromagnetic film 5, part of the solidsecond antiferromagnetic film 5 which is not covered with the resistlayers 8 is removed by etching, and the resist layers 8 are thenremoved, thereby forming the second antiferromagnetic layers 5.

In the step shown in FIG. 23, a solid electrode film 6 is formed on thesecond antiferromagnetic layers 5 and the free magnetic layer 4, and onthe solid electrode film 6, a resist film 7 is formed. In the step shownin FIG. 23, a space for the track width Tw is formed in the resist film7 in the track width direction (X direction in the figure), therebyforming the resist layers 7. The track width Tw is smaller than thespace T1 formed between the second antiferromagnetic layers 5.

In the step shown in FIG. 24, part of the solid electrode film 6 whichis not covered with the resist layers 7 is removed by ion milling orreactive ion etching, thereby exposing the upper surface of the freemagnetic layer 4. Since the other parts of the solid electrode film 6,which are not removed and which form the electrode layers 6, overlap theupper surfaces of the second antiferromagnetic layers 5 and the freemagnetic layer 4, and sense current tends to flow easily from theelectrode layers 6 to the free magnetic layer 4 side (the flow of thesense current is indicated by the arrows in FIG. 24), it has beenanticipated that the problems described above, that is, the increase inelement resistance and the side reading, can be simultaneously solved.

In recent years, the track width TW has been decreased concomitant withthe trend toward higher recording density. When the track width Tw isdecreased, dead regions (regions which do not directly contribute toreproduction) positioned under the second antiferromagnetic layers 5 andin the very vicinity of both sides of the track width tend to have alarger ratio of the whole area, and as a result, decrease inreproduction output cannot be prevented. However, when the structure isformed so that the electrode layers 6 overlap the free magnetic layer bythe manufacturing steps shown in FIGS. 22 to 24, the dead regions can bedecreased to some extent as compared to those of the magnetic sensorshown in FIG. 22 since the space between the second antiferromagneticlayers 5 can be increased, and hence it has been expected that thereproduction output can be effectively improved by the structuredescribed above.

In addition, in the structure in which the electrode layers 6 overlapthe free magnetic layer 4 while the track width Tw is decreased, as isthe magnetic sensor shown in FIG. 24, widths T2 and T3 (hereinafterreferred to as “overlap length”) of the overlap portions in the trackwidth direction are approximately {fraction (1/100)}μm, and hence thealignment accuracy becomes important when the electrode layers 6 areformed.

However, in the manufacturing steps shown in FIGS. 22 to 24, the secondantiferromagnetic layers 5 each having a predetermined shape are firstformed using the resist layers 8 in the step shown in FIG. 22, and afterthe resist layers 8 are removed, in the step shown in FIG. 23, theoverlap structure must be formed by the electrode layers 6 again usingthe resist layers 7.

That is, mask alignment must be performed at least twice, and since thealignment accuracy is approximately ±{fraction (1/100)}μm for formingthe resist layers 7, when the alignment is deviated by onlyapproximately {fraction (1/100)}μm, the overlap lengths T2 and T3 of theelectrode layer 6 at both sides are not equivalent to each other andbecome significantly different from each other. In addition, in theworst case, one of the electrode layers 6 may be formed so as to overlapthe free magnetic layer 4, and the other electrode layer 6 may be formedonly on the second antiferromagnetic layer 5 and may not overlap thefree magnetic layer 4.

As described above, in the past, it has been considered that theincrease in element resistance and the generation of side reading can besuppressed by forming the electrode layers 6 so as to overlap the freemagnetic layer 4. However, when the magnetic sensor is actuallymanufactured, it has been difficult to form equivalent overlap lengthsof the electrode layers formed at the left and the right sides sincemask alignment must be performed twice, and as a result, the generationof side reading and the increase in element resistance could not beeffectively suppressed by the magnetic sensor in which the overlaplengths of the electrode layers at the left and the right are differentfrom each other.

SUMMARY OF THE INVENTION

Accordingly, the present invention was made in order to solve theproblems described above, and particularly, an object of the presentinvention is to provide a magnetic sensor having an overlap structure,in which overlap electrode layers at the left and the right sides haveshapes equivalent to each other, and a manufacturing method thereof. Theoverlap structure mentioned above can be obtained by forming the overlapelectrode layers described above separately from electrode layersprovided on second antiferromagnetic layers.

A magnetic sensor according to the present invention, which has amultilayer film formed of a first antiferromagnetic layer, a fixedmagnetic layer, a nonmagnetic material layer, and a free magnetic layerprovided in that order from the bottom, comprises: secondantiferromagnetic layers which are disposed with a predetermined spaceprovided therebetween in the track width direction and which areprovided on the upper surface of the multilayer film; first electrodelayers formed on the respective second antiferromagnetic layers; andsecond electrode layers disposed with a predetermined space providetherebetween in the track width direction, the second electrode layersbeing provided directly on or indirectly above at least internal endsurfaces in the width direction of the first electrode layers and thesecond antiferromagnetic layers and parts of the upper surface of themultilayer film.

In the present invention, the first electrode layers are preferablyformed in a step separate from that for the second electrode layers.

In the present invention, as described above, the first electrode layersare formed on the second antiferromagnetic layers formed with apredetermined space provided therebetween in the track width direction.In a separate step from that for the first electrode layers, the secondelectrode layers are formed directly on or indirectly above the internalend surfaces of the first electrode layers and the secondantiferromagnetic layers and parts of the upper surface of themultilayer film. That is, the second electrode layers each directly orindirectly overlap the upper surface of the multilayer film.

According to one embodiment of the present invention, since the secondelectrode layers at the left and the right sides can be formed so as tosymmetrically overlap the upper surface of the multilayer, decrease inelement resistance and reduction of side reading can be effectivelyachieved even when the track has been narrowed. In addition, thereproduction output can be more effectively improved as compared to thatin the past.

In the present invention, since the first electrode layers are formed ina step separate from that for the second electrode layers, the firstelectrode layers may be formed of a material different from that for thesecond electrode layers. As a result, for example, the first electrodelayers may be formed of a material having ductility lower than that ofthe second electrode layers.

When the first electrode layer and the second electrode layer are bothformed of a soft material, such as Au, having high ductility, and whenpolishing is performed in a slider-forming step or the like, smearingoccurs, and hence short circuiting occurs between the electrode layerand an upper shield layer or a lower shield layer, resulting indestruction of reproduction functions of the magnetic sensor. It isimportant that the second electrode layers forming the overlap structurehave high conductivity, and according to the structure of the presentinvention, even when the first electrode layer has conductivity lowerthan that of the second electrode layer, the reproductioncharacteristics are not so much degraded. In addition, the area in whichthe first electrode layer is formed tends to be larger than that inwhich the second electrode layer is formed. Accordingly, when the firstelectrode layer is formed of a material having ductility lower than thatof the second electrode layer, the generation of smearing can beeffectively suppressed.

In the present invention, the first electrode layer is preferably formedof at least one of Cr, Rh, Ru, Ta, and W, or an alloy of Au containingat least one of Pd and Cr, and the second electrode layer is preferablyformed of at least one of Au, Cu, and Ag.

In addition, in the present invention, the second electrode layers arepreferably formed only on the internal end surfaces and the parts of theupper surface of the multilayer film.

In the present invention, stop layers are preferably provided under thesecond electrode layers and are preferably composed of a material havingan etching rate lower than that of the second electrode layers.

The stop layers are preferably formed of at least one element selectedfrom the group consisting of Ta, Cr, V, Nb, Mo, W, Fe, Co, Ni, Pt, andRh. The stop layers each preferably have a laminate structure composedof a Cr layer and a Ta layer provided in that order from the bottom.

In the present invention, the internal end surfaces of the secondantiferromagnetic layers and the respective internal end surfaces of thefirst electrode layers preferably form continuous surfaces.

A method for manufacturing a magnetic sensor, according to the presentinvention, comprises the following steps. The steps are: step (a) offorming a multilayer film including a first antiferromagnetic layer, afixed magnetic layer, a nonmagnetic material layer, and a free magneticlayer provided in that order on a substrate; step (b) of forming secondantiferromagnetic layers, which are disposed on two side portions of themultilayer film in the track width direction, and first electrode layerson the second antiferromagnetic layers; and step (c) of forming secondelectrode layers directly on or indirectly above at least internal endsurfaces in the track width direction of the first electrode layers andthe second antiferromagnetic layers and parts of the upper surface ofthe multilayer film, the second electrode layers being provided with apredetermined space provided therebetween in the width direction.

According to steps (a) to (c), the first electrode layers and the secondelectrode layers can be formed in separate steps, and since it is notnecessary to perform mask alignment twice as was in the past, an overlapstructure can be precisely formed in which overlap lengths, which arethe thickness of the electrodes, at the left and the right sides areequivalent to the other.

According to the present invention, a method for manufacturing amagnetic sensor, comprises: step (a) of forming a multilayer filmincluding a first antiferromagnetic layer, a fixed magnetic layer, anonmagnetic material layer, and a free magnetic layer provided in thatorder on a substrate; step (b) of forming second antiferromagneticlayers, which are disposed on two side portions of the multilayer filmin the track width direction, and first electrode layers on the secondantiferromagnetic layers; step (d) of forming a solid second electrodefilm on the upper surfaces of the first electrode layers, internal endsurfaces in the track width direction of the first electrode layers andthe second antiferromagnetic layers, and the upper surface of themultilayer film; and step (e) of removing a center part of the solidsecond electrode film formed on the upper surface of the multilayerfilm, whereby second electrode layers with a predetermined spaceprovided therebetween in the track width direction are formed on theinternal end surfaces and parts of the upper surface of the multilayerfilm.

In steps (d) and (e), mask alignment of a resist performed in the pastis not necessary, and the second electrode layers can be formed in astep separate from that for the first electrode layers so that theoverlap lengths at the left and the right sides are equivalent to eachother.

The method for manufacturing a magnetic sensor, according to the presentinvention, may further comprise forming a solid stop film on the uppersurfaces of the first electrode layers, the internal end surfaces in thetrack width direction of the first electrode layers and the secondantiferromagnetic layers, and the upper surface of the multilayer filmafter step (b) is performed; and after a part of the solid stop film isexposed by removing the center part of the solid second electrode filmin step (e), removing the part of the solid stop film.

In the present invention, the solid stop film is preferably formed of amaterial having an etching rate lower than that of the solid secondelectrode film. In particular, the solid stop film is preferably formedof at least one element selected from the group consisting of Ta, Cr, V,Nb, Mo, W, Fe, Co, Ni, Pt, and Rh. In addition, the solid stop film ismore preferably formed of a Cr layer and a Ta layer provided in thatorder from the bottom.

When the center part of the solid second electrode film formed on themultilayer film is removed in step (e), the multilayer film may bedamaged by overetching in some cases in this step. Accordingly, in thecase in which the solid stop film is provided in order to avoid thedamage described above, even when the solid second electrode film formedon the solid stop film is removed by etching, and over etching is thenfurther performed, the multilayer film is prevented from being damagedby the etching.

In the present invention, it is preferable that the solid secondelectrode film provided on the upper surfaces of the first electrodelayers be entirely removed in step (e).

In the present invention, in step (d), the solid second electrode filmis preferably formed by sputtering with a sputtering angle inclined fromthe direction perpendicular to the substrate so that the thicknessthereof on the internal end surfaces is larger than each of those on theupper surface of the multilayer film and on the upper surfaces of thefirst electrode layers.

The difference in thickness at the individual positions of the solidsecond electrode film formed by sputtering is significantly important.As described above, when the solid second electrode film is sputtered,the thickness thereof on the internal end surfaces must be larger thaneach of those on the upper surface of the multilayer film and on theupper surfaces of the first electrode layers.

In step (e), the center part of the solid second electrode film, whichis formed on the upper surface of the multilayer film with or withoutanother layer provided therebetween, is removed, and in this step, partsof the solid second electrode film formed on the internal end surfacesare also removed. However, in the present invention, the solid secondelectrode film formed on the internal end surfaces must remain forforming the second electrode layers. Accordingly, when the thickness ofthe solid second electrode film on the internal end surfaces is smallerthan that on the upper surface of the multilayer film, before the solidsecond electrode film on the upper surface of the multilayer film isentirely removed, the solid second electrode film formed on the internalend surfaces may be removed faster than that described above in somecases. Hence, in the present invention, the solid second electrode film,which is to be formed into the second electrode layers, is formed bysputtering with a sputtering angle inclined from the directionperpendicular to the substrate, and as a result, the thickness of thesolid second electrode film on the internal end surfaces is larger thaneach of those on the upper surface of the multilayer film and on theupper surfaces of the first electrode layers.

In the present invention, when the solid second electrode film is formedin step (d), the thickness thereof on the upper surface of themultilayer film is preferably smaller than each of those on the uppersurfaces of the first electrode layers.

In the present invention, in step (e) of removing the center part of thesolid second electrode film formed on the upper surface of themultilayer film by milling, the milling angle is preferably set close toperpendicular to the substrate as compared to the sputtering angle usedfor forming the solid second electrode film.

Accordingly, since the center part of the solid second electrode filmcan be appropriately removed, the second electrode layers having apredetermined thickness can be formed on the internal end surfaces, andhence the overlap structure can be precisely formed in which thethicknesses of the second electrode layers at the left side and theright side are equivalent to each other.

In addition, in the present invention, the first electrode layers arepreferably formed of a nonmagnetic conductive material different fromthat for the second electrode layers. Furthermore, the first electrodelayers are preferably formed of a material having ductility lower thanthat for the second electrode layers.

In the present invention, the first electrode layers are preferablyformed of at least one of Cr, Rh, Ru, Ta, and W, or an alloy of Aucontaining at least one of Pd and Cr, and the second electrode layersare preferably formed of at least one of Au, Cu, and Ag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly cross-sectional view showing the structure of amagnetic sensor according to a first embodiment of the presentinvention, the sensor being viewed from an opposing face side opposing arecording medium;

FIG. 2 is a partly cross-sectional view showing the structure of amagnetic sensor according to a second embodiment of the presentinvention, the sensor being viewed from an opposing face side opposing arecording medium;

FIG. 3 is a partly cross-sectional view showing the structure of amagnetic sensor according to a third embodiment of the presentinvention, the sensor being viewed from an opposing face side opposing arecording medium;

FIG. 4 is a partly, enlarged, cross-sectional view showing oneembodiment of a free magnetic layer of the present invention, theembodiment being-viewed from an opposing face side opposing a recordingmedium;

FIG. 5 is a partly, enlarged, cross-sectional view showing anotherembodiment of a free magnetic layer of the present invention, theembodiment being viewed from an opposing face side opposing a recordingmedium;

FIG. 6 is a partly, enlarged, cross-sectional view showing anotherembodiment of a free magnetic layer of the present invention, theembodiment being viewed from an opposing face side opposing a recordingmedium;

FIG. 7 is a partly, enlarged, cross-sectional view showing anotherembodiment of a free magnetic layer of the present invention, theembodiment being viewed from an opposing face side opposing a recordingmedium;

FIG. 8 is a partly cross-sectional view showing the structure of amagnetic sensor according to a fourth embodiment of the presentinvention, the sensor being viewed from an opposing face side opposing arecording medium;

FIG. 9 is a partly schematic view showing the state of the rear side inthe height direction of a magnetic sensor in one step of a manufacturingmethod of the present invention;

FIG. 10 is a schematic view showing a step of manufacturing the magneticsensor shown in FIG. 1;

FIG. 11 is a schematic view showing a step following the step in FIG.10;

FIG. 12 is a schematic view showing a step following the step in FIG.11;

FIG. 13 is a schematic view showing a step following the step in FIG.12;

FIG. 14 is a schematic view showing a step following the step in FIG.13;

FIG. 15 is a schematic view showing a step following the step in FIG.14;

FIG. 16 is a schematic view showing a step following the step in FIG.15;

FIG. 17 is a schematic view showing a step of manufacturing the magneticsensor shown in FIG. 3;

FIG. 18 is a schematic view showing a step following the step in FIG.17;

FIG. 19 is a schematic view showing a step following the step in FIG.18;

FIG. 20 is a partly cross-sectional view showing the structure of amagnetic sensor according to a fifth embodiment of the presentinvention, the sensor being viewed from an opposing face side opposing arecording medium;

FIG. 21 is a partly cross-sectional view showing the structure of arelated magnetic sensor viewed from an opposing face side opposing arecording medium;

FIG. 22 is a schematic view showing a step of manufacturing anotherrelated magnetic sensor;

FIG. 23 is a schematic view showing a step following the step in FIG.22; and

FIG. 24 is a schematic view showing a step following the step in FIG.23.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a partly cross-sectional view of the structure of a magneticsensor (spin-valve type thin-film element) of the present invention, thesensor being viewed from an opposing face side opposing a recordingmedium.

Reference numeral 20 indicates a substrate. On the substrate 20, a seedlayer 21 formed of a NiFe alloy, a NiFeCr alloy, Cr, or the like isprovided. The seed layer 21 is composed, for example, of 60 atomicpercent of Ni_(0.8)Fe_(0.2) and 40 atomic percent of Cr and has athickness of 60 Å.

On the seed layer 21, a first antiferromagnetic layer 22 is formed. Thefirst antiferromagnetic layer 22 is formed of, for example, a PtMnalloy, an X—Mn alloy (X is at least one element selected from the groupconsisting of Pd, Ir, Rh, Ru, Os, Ni, and Fe), or a Pt—Mn—X′ alloy (X′is at least one element selected from the group consisting of Pd, Ir,Rh, Ru, Au, Ag, Os, Cr, Ni, Ar, Ne, Xe, and Kr).

As the first antiferromagnetic layer 22, when the alloy described aboveis used, and heat treatment is then performed, an exchange coupling filmof the first antiferromagnetic layer 22 and a fixed magnetic layer 23,which generated a strong exchange coupling magnetic field, can beobtained. In particular, when a PtMn alloy is used, the exchangecoupling film formed of the first antiferromagnetic layer 22 and thefixed magnetic layer 23 can be obtained which has an exchange couplingmagnetic field of 48 kA/m or more, such as more than 64 kA/m, and anextremely high blocking temperature of 380° C. at which the exchangecoupling magnetic field disappears.

The alloys described above are each an irregular crystal having theface-centered cubic (fcc) structure right after the film formation andis then transformed into a CuAuI type regular crystal having theface-centered tetragonal (fct) structure by heat treatment.

The film thickness of the first antiferromagnetic layer 22 around thecenter in the track width direction is in the range of from 80 to 300 Å.

On the first antiferromagnetic layer 22, the fixed magnetic layer 23 isformed. The fixed magnetic layer 23 has an artificial ferrimagneticstructure. The fixed magnetic layer 23 has a three-layer structurecomposed of magnetic layers 24 and 26 and a nonmagnetic interlayer 25provided therebetween.

The magnetic layers 24 and 26 are formed of a magnetic material, such asa NiFe alloy, Co, a CoNiFe alloy, a CoFe alloy, or a CoNi alloy. Themagnetic layers 24 and 26 are preferably formed of the same material.

In addition, the nonmagnetic interlayer 25 is formed of a nonmagneticmaterial comprising at least one of Ru, Rh, Ir, Cr, Re, Cu, and an alloycontaining at least one element mentioned above. In particular, thenonmagnetic interlayer 25 is preferably formed of Ru.

On the fixed magnetic layer 23, a nonmagnetic material layer 27 isformed. The nonmagnetic material layer 27 is a layer which interfereswith magnetic coupling between the fixed magnetic layer 23 and a freemagnetic layer 28, which allows sense current to primarily flowtherethrough, and which is preferably formed of a conductive nonmagneticmaterial such as Cu, Cr, Au, or Ag. In particular, the nonmagneticmaterial layer 27 is preferably formed of Cu.

On the nonmagnetic material layer 27, the free magnetic layer 28 isformed. In the embodiment shown in FIG. 1, the free magnetic layer 28has a two-layer structure. Reference numeral 29 indicates adiffusion-blocking layer formed of Co, CoFe, or the like. Thisdiffusion-blocking layer 29 inhibits the mutual diffusion between thefree magnetic layer 28 and the nonmagnetic material layer 27. Inaddition, on this diffusion-blocking layer 29, a magnetic material layer30 formed of a NiFe alloy or the like is provided.

Hereinafter, the laminate formed of from the substrate 20 to the freemagnetic layer 28 is called a multilayer film 40.

On the free magnetic layer 28, second antiferromagnetic layers 31 areformed. As is the first antiferromagnetic layer 22, the secondantiferromagnetic layers 31 are each formed of, for example, a PtMnalloy, an X—Mn alloy (X is at least one element selected from the groupconsisting of Pd, Ir, Rh, Ru, Os, Ni, and Fe), or a Pt—Mn—X′ alloy (X′is at least one element selected from the group consisting of Pd, Ir,Rh, Ru, Au, Ag, Os, Cr, Ni, Ar, Ne, Xe, and Kr).

The second antiferromagnetic layers 31 are disposed with a spaceprovided therebetween in the track width direction; however, as shown inFIG. 1, a connecting layer 31 e having a small thickness as compared tothat of each of the second antiferromagnetic layers 31 may be providedtherebetween and may be formed of the same material as that for thesecond antiferromagnetic layers 31. In the embodiment shown in FIG. 1,the case will be described in which the second antiferromagnetic layers31 are provided at two side portions C, the connecting portion 31 e isprovided at a center portion D, and since the material for the secondantiferromagnetic layers 31 is the same as that for the connecting layer31 e, these three layers are formed simultaneously.

In the embodiment shown in FIG. 1, on the two second antiferromagneticlayers 31 at the two side portions C, first stop layers 33 formed of Ta,Cr, or the like are provided. As shown in FIG. 1, on the first stoplayers 33, first electrode layers 34 are formed.

In this embodiment, internal end surfaces 34 a of the first electrodelayers 34 in the track width direction and respective internal endsurfaces 31 a of the second antiferromagnetic layers 31 in the trackwidth direction form continuous surfaces. In the embodiment shown inFIG. 1, the distances between the internal end surfaces 31 a of thesecond antiferromagnetic layers 31 and between the internal end surfaces34 a of the first electrode layers 34 are gradually increased from thelower side to the upper side, thereby forming inclined surfaces orcurved surfaces at the two sides in the track width direction.

As shown in FIG. 1, on the internal end surfaces 34 a of the firstelectrode layers 34 and the respective internal end surfaces 31 a of thesecond antiferromagnetic layers 31, second stop layers 35 are formed.The second stop layers 35 are formed of Cr, Ta, or the like. Inaddition, internal front portions 35 a of the second stop layers 35extend to the surface of the connecting layer 31 e provided between thesecond antiferromagnetic layers 31.

In the embodiment shown in FIG. 1, on the second stop layers 35, secondelectrode layers 36 are formed. That is, the second electrode layers 36are each continuously formed on the internal end surfaces 34 a and 31 aof the first electrode layer 34 and the second antiferromagnetic layer31 and part of the upper surface of the multilayer film 40 with anadditional layer provided therebetween. In FIG. 1, the track width Tw isdefined by a space between the second electrode layers 36 in the trackwidth direction (X direction in the figure).

In the embodiment shown in FIG. 1, a protective layer 37 is continuouslyformed on upper surfaces 34 b of the first electrode layers 34, thesecond electrode layers 36, and the upper surface of the connectinglayer 31 e which is provided at the center portion D and between theantiferromagnetic layers 31.

The features of the magnetic sensor according to the embodiment shown inFIG. 1 will be described.

In the embodiment shown in FIG. 1, the second antiferromagnetic layers31 at the two side portions C on the multilayer film 40 and theconnecting layer 31 e at the central portion D thereon are formed, andabove the second antiferromagnetic layers 31 at the two side portions C,the first electrode layers 34 are formed with the first stop layers 33provided therebetween. The second electrode layers 36 formed in a stepseparate from that for the first electrode layers 34 are eachcontinuously formed above (that is, to overlap) the internal end surface34 a of the first electrode layer 34, the internal end surface 31 of thesecond antiferromagnetic layer 31, and the upper surface of themultilayer film 40 with other layers (which indicate the second stoplayer 35 and the connecting layer 31 e) provided therebetween, and thespace between the second electrode layers 36 in the track widthdirection (X direction in the figure) defines the track width Tw.

The difference of the magnetic sensor of this embodiment from therelated example shown in FIG. 24 is that one type of electrode layer 6is formed so as to overlap the multilayer film from the secondantiferromagnetic layer 5 side in the example shown in FIG. 24, and onthe other hand, in the present invention, the first electrodes 34provided on the second antiferromagnetic layers 31 at the two sideportions C are formed separately from the second electrode layers 36which overlap the multilayer film 40.

As described later in detail, in the manufacturing method of the presentinvention, mask alignment of a resist layer for forming the secondelectrode layers 36 is not necessary, and as a result, the secondelectrode layers 36 disposed with a predetermined space therebetween inthe track width direction can be precisely formed so as to havethicknesses T4 thereof equivalent to each other even when a narrowertrack is formed. The thickness T4 corresponds to the overlap length andis preferably in the range of from 50 to 500 Å.

According to the present invention, compared to the related exampleshown in FIG. 23, the decrease in element resistance and reduction ofgeneration of side reading can be effectively achieved. In addition, byforming the overlap structure in which the thicknesses of the electrodesdisposed with a predetermined space therebetween are equivalent to eachother, the reproduction output can be effectively improved as comparedto that of the related example shown in FIG. 23.

In addition, in the present invention, since the first electrode layers34 and the second electrode layers 36 can be formed separately, thefirst electrode layers 34 can be formed of a material different fromthat for the second electrode layers 36. Hence, materials for the firstelectrode layer 34 and the second electrode layer 36 can be more freelyselected.

In the present invention, the second electrode layers 36 are preferablyformed of a nonmagnetic conductive material having high conductivity.For example, the second electrode layers 36 are preferably formed of atleast one of Au, Cu, Ag, and the like. The reason the second electrodelayers 36 preferably have high conductivity is that sense current isallowed to easily flow through the second electrode layers 36 to themultilayer film 40 side.

In addition, the first electrode layers 34 also preferably have highconductivity; however, in this embodiment, since the first layers do notoverlap the multilayer film 40, the conductivity of the first electrodelayers 34 may be lower than that of the second conductive layers 36.However, the conductivity of the first electrode layers 34 is preferablyhigher than that of the second antiferromagnetic layers 31.

In the case in which the first electrode layer 34 is formed of amaterial such as Au having high conductivity, as is the second electrodelayer 36, when the surface of the first electrode layer 34 is polishedin a slider-forming step, smearing of the electrode layer may occursince Au has high ductility. Since the area in which the smearing occursis preferably reduced as small as possible for improving thereproduction output, and the area in which the first electrode layer 34is formed tends to be larger than that of the second electrode layer 36,the first electrode layer 34 which is not so much required to have highconductivity as compared to the second electrode layer 36 is preferablyformed of a nonmagnetic conductive material having low ductility insteadof that having high conductivity. The first electrode layer 34 ispreferably formed of at least one of Cr, Rh, Ru, Ta, and W, or an alloyof Au containing at least one of Pd and Cr. However, when the smearingmay not cause any problem in the area in which the first electrode layer34 is formed, the first electrode layer 34 may be formed of anonmagnetic conductive material similar to that for the second electrodelayer 36. The degree of “ductility” can be measured by a “ductilitytest”; however, when the material is in the form of a thin film as inthe present invention, the “ductility” cannot be measured. Hence,selection may be performed by measuring the degree of ductility of amaterial in the bulk form to be used for the electrode layer, ormaterials for the first and the second electrode layers 34 and 36 may beselected based on general chemical information already disclosed inpapers and the like.

Next, the area in which the second electrode layer 36 is formed will bedescribed. In the embodiment shown in FIG. 1, the second electrodelayers 36 are each formed above the internal end surface 34 a of thefirst electrode layer 34, the internal end surface 31 a of the secondantiferromagnetic layer 31, and part of the upper surface of themultilayer film 40 with an additional layer provided therebetween. Asshown in FIG. 2 (partly cross-sectional view showing a magnetic sensorof a second embodiment of the present invention, the sensor being viewedfrom an opposing face side opposing a recording medium), the secondelectrode layers 36 may be formed so as to extend onto the uppersurfaces 34 b of the first electrode layers 34; however, in this case,the following points must be taken into consideration.

In the manufacturing method described later, a solid second electrodefilm 36 s, which is to be formed into the second electrode layers 36, isfirst formed on the first electrode layers 34, the internal end surfaces31 a and 34 a, and the central portion D of the multilayer film 40 bysputtering, and in addition, the solid second electrode film 36 s mayalso be formed on an insulating layer 70 widely extending in the heightdirection (Y direction in the figure) from the multilayer film 40.

FIG. 9 is a partly schematic view showing part of the magnetic sensorshown in FIG. 2.

Since the distances in the track width direction (X direction in thefigure) between the internal end surfaces 31 a of the secondantiferromagnetic layers 31 and between the internal end surfaces 34 aof the first electrode layers 34 are gradually increased from the faceopposing a recording medium to the rear side in the height direction (Ydirection in the figure), the internal end surfaces 31 a of the secondantiferromagnetic layers 31 and the respective internal end surfaces 34a of the first electrode layers 34 form inclined or curved surfaces. Inaddition, from the rear end of the multilayer film 40 in the heightdirection, the insulating layer 70 is widely formed. As described above,the solid second electrode film 36 s is also formed on this insulatinglayer 70. The thickness of the solid second electrode film 36 s formedon the insulating layer 70 is approximately equivalent to that formed onthe upper surface 34 b of the first electrode layer 34. However, thethickness of the solid second electrode film 36 s, formed in a verynarrow region A on the multilayer film 40 at the opposing face sideopposing a recording medium, is smaller than each thickness of the solidsecond electrode film 36 s formed on the insulating layer 70 and theupper surface 34 b of the first electrode layer 34. This is due to aso-called shadow effect, and as described later, the solid secondelectrode film 36 s formed on the region A of the multilayer film 40 isfinally removed by etching.

However, even when the solid second electrode film 36 s formed on theregion A of the multilayer film 40 is entirely removed, since thethicknesses of the solid second electrode film 36 s formed on theinsulating layer 70 and the upper surfaces 34 b of the first electrodelayers 34 are large, parts thereof still remain after the etchingmentioned above is performed. Because of the solid second electrode film36 s (shown by oblique lines in the figure) remaining on the insulatinglayer 70, a problem may arise. When the solid second electrode film 36 swhich remains, for example, on the insulating layer 70 is in electricalcontact with that remaining on the internal end surfaces 31 a of thesecond antiferromagnetic layers 31, sense current may flow to the solidsecond electrode film 36 s side remaining on the insulating layer 70,and as a result, the reproduction characteristics may not be effectivelyimproved.

Accordingly, since the entire solid second electrode film 36 s remainingon the insulating layer 70 is preferably removed, after the solid secondelectrode film 36 s formed on the region A is totally removed, etchingis further performed for removing every solid second electrode film 36 son the insulating layer 70, and as a result, the solid second electrodefilm 36 s on the upper surfaces 34 b of the first electrode layers 34are also entirely removed as shown in FIG. 1. For example, at the stageshown in FIG. 9, when the magnetic sensor is selectively protected by aresist or the like in order to only remove the solid second electrodefilm 36 s on the insulating layer 70, parts of the solid secondelectrode film 36 s also remain above the upper surfaces 34 b of thefirst electrode layers 34 as shown in FIG. 2 and are used as the secondelectrode layers 36.

Next, the second stop layers 35 will be described. The second stoplayers 35 are formed under the second electrode layers 36 as shown inFIG. 1. The second stop layers 35 are preferably formed of at least oneelement selected from the group consisting of Ta, Cr, V, Nb, Mo, W, Fe,Co, Ni, Pt, and Rh.

Among essential characteristics as the second stop layer 35, theconductivity is first required, and secondary, an etching rate lowerthan that of the second electrode layer 36 is required. The reason theconductivity is the essential characteristic is that sense current flowsfrom the second electrode layer 36 to the multilayer film 40 sidethrough the second stop layer 35. Next, the reason the etching ratelower than that of the second electrode layer 36 is the essentialcharacteristic is that in the manufacturing method described later, evenwhen overetching is performed in a step of removing the solid secondelectrode film 36 s formed on the central portion D of the multilayerfilm 40, a layer under the solid second electrode film 36 s must beprevented from being damaged by the etching described above. Even whenthe overetching is performed, since the second stop layer 35 having alow etching rate is only exposed and may not be totally removed at allby this overetching, the layer provided thereunder is prevented frombeing damaged by the etching.

In the embodiment shown in FIG. 1, the second stop layer 35 is notpresent between internal end surfaces in the track width direction (Xdirection in the figure) of the second electrode layers 36; however, asshown by a dotted line, the second stop layer 35 may remain partlybetween the second electrode layers 36. In addition, in the embodimentin FIG. 1, the second stop layers 35 are not present on the uppersurfaces 34 b of the first electrode layers 34; however, the second stoplayers 35 may remain on the upper surfaces 34 b of the first electrodelayers 34. According to the manufacturing method described later, on theupper surfaces 34 b of the first electrode layers 34, mask layers 42 andthe second stop layers 35 may remain in some cases.

In the case in which the second stop layer 35 is formed of a materialwhich is not etched by reactive ion etching (RIE) or which is unlikelyto be etched thereby, even when the second stop layer 35 is exposed byoveretching the solid second electrode film 36 s, the second stop layer35 is not substantially influenced by this etching. Although themanufacturing method described later includes a step of removing thesolid second electrode film 36 s above the center portion D by reactiveion etching, for example, when the second stop layer 35 is formed of amaterial which is not etched by the reactive ion etching mentionedabove, of course, the second stop layer 35 is not etched thereby, andhence the material described above may be used for forming the secondstop layer 35.

In addition, the second stop layer 35 may have a laminate structurecomposed of a Cr layer and a Ta layer provided in that order from thebottom. The Cr layer easily diffuses with Au. When diffusion occurs, itis not preferable since the element resistance is increased. When thesecond electrode layer 36 is formed, for example, of Au, and the secondstop layer 35 is formed from a Cr layer, the Ta layer mentioned above ispreferably provided between the Cr layer and the second electrode layer36 in order to prevent the diffusion described above. In addition, thesecond stop layer 35 may have a laminate structure composed of a Talayer, a Cr layer, and a Ta layer in that order. When the firstelectrode layer 34 is formed of a material which easily diffuses with aCr layer, by forming the second stop layer 35 having the three-layerstructure described above, the diffusion of the Cr layer with the firstelectrode layer 34 can be suppressed.

Although the second stop layer 35 may not be formed, it is preferablyformed. As described with reference to FIG. 9, the reason for this isthat since the solid second electrode film 36 s remaining on theinsulating layer 70 must be removed by etching even after the solidsecond electrode film 36 s on the region A was entirely removed, whenthe second stop layer 35 is not provided, the multilayer film 40 or theconnecting layer 31 e provided between the second antiferromagneticlayers 31, which is formed on the multilayer film 40, are influenced bythis overetching. However, as described with reference to FIG. 9, inorder to remove only the solid second electrode film 36 s remaining onthe insulating layer 70 by etching, when a resist is provided to protectthe magnetic sensor, the magnetic sensor will not receive any influenceof the etching described above, and hence the second stop layer 35 maynot be formed.

In the embodiment shown in FIG. 1, the protective layer 37 iscontinuously formed on the upper surfaces 34 b of the first electrodelayers 34, the second electrode layers 36, and the central portion D ofthe multilayer film 40. The protective layer 37 is formed of an oxide ofTa or the like and serves to appropriately protect the magnetic sensorshown in FIG. 1 from oxidation. For the formation of the protectivelayer 37, a Ta film is formed and is then oxidized. The thickness of theprotective layer 37 is, for example, in the range of from approximately20 to 50 Å.

In addition, in the embodiment shown in FIG. 1, the first stop layers 33are provided between the second antiferromagnetic layers 31 and thefirst electrode layers 34. As is the second stop layer 35, the firststop layer 33 is formed of Cr, Ta, or the like. The first stop layer 33may not be formed; however, when it is formed, the etching amount of theconnecting layer 31 e provided on the central portion D can beappropriately adjusted while SIMS (secondary ion mass spectrometer)measurement is performed for determining an appropriate etching depth ofthe connecting layer 31 e provided between the second antiferromagneticlayers 31.

In the embodiment shown in FIG. 1, the connecting layer 31 e having asmall thickness is formed on the central portion D; however, as shown inFIG. 3 (partly cross-sectional view of the structure of a magneticsensor of a third embodiment according to the present invention, thesensor being viewed from an opposing face side opposing a recordingmedium), the connecting layer 31 e may not be provided on the centralportion D.

When the connecting layer 31 e is provided on the central portion D asshown in FIG. 1, a film thickness h1 thereof is preferably 50 Å or less.The thickness of connecting layer 31 e on the central portion 31 iscontrolled so that an exchange coupling magnetic field with the freemagnetic layer 28 is not generated or is very weak even when annealingin a magnetic field is performed. The reason for this is that whenconnecting layer 31 e having a large thickness is provided on thecentral portion D, a strong exchange coupling magnetic filed with thefree magnetic layer 28 is generated, and the magnetization of the freemagnetic layer 28 at the central portion D is fixed in the X directionshown in the figure, resulting in degradation of the reproductionsensitivity.

In the magnetic sensor shown in FIG. 2, as described above, the secondelectrode layers 36 are formed to extend onto the upper surfaces 34 b ofthe first electrode layers 34 with the second stop layer 35 providedtherebetween. In addition to the area under the second electrode layers36, the second stop layer 35 is formed over the entire surface on thecentral portion D on which the second electrode layer 36 is not formed.In this case, the structures of the other layers are equivalent to thosedescribed above with reference to FIG. 1, descriptions thereof areomitted.

In the magnetic sensor shown in FIG. 3, which is different from thatshown in FIG. 1, the first stop layers 33 are not present between thesecond antiferromagnetic layers 31 and the first electrode layers 34. Inaddition, in the magnetic sensor shown in FIG. 3, the connecting layer31 e is not formed on the center portion D of the multilayer film 40,and the two second antiferromagnetic layers 31 are formed only on thetwo side portions C.

In addition, in the magnetic sensor shown in FIG. 3, at the two sideportions C, ferromagnetic layers 51 formed of a NiFe alloy of the likeare each provided between the second antiferromagnetic layer 31 and thefree magnetic layer 28. In this embodiment, when an exchange couplingmagnetic field is generated between the ferromagnetic layer 51 and thesecond antiferromagnetic layer 31 so that the magnetization of theferromagnetic layer 51 is fixed in the X direction shown in the figure,the magnetization of the free magnetic layer at each side portion C isalso fixed in the X direction by interlayer coupling with theferromagnetic layer 51.

In the magnetic sensor shown in FIG. 3, a nonmagnetic layer 41 composedof Ru or the like is formed on the central portion D of the multilayerfilm 40 and between the second strop layers 35. This nonmagnetic layer41 is formed separately from the second stop layers 35 which are eachformed extending from one of two ends of the nonmagnetic layer 41 to theinternal end surface 31 a of the second antiferromagnetic layer 31 andthe internal end surface 34 a of the first electrode layer 34. Thenonmagnetic layer 41 is preferably formed of at least one selected fromthe group consisting of Ru, Re, Pd, Os, Ir, Pt, Au, and Rh.

The reason the structure in FIG. 3 is different from that describedabove is that a step of forming the first electrode layers 34 and thepreceding steps are different from those shown in FIGS. 1 and 2. Thestructures of other layers or the like are equivalent to those describedabove with reference to FIG. 1, descriptions thereof are omitted.

FIG. 4 is a partly enlarged cross-sectional view primarily showing thefree magnetic layer 28 viewed from an opposing face side opposing arecording medium.

The free magnetic layer 28 according to the embodiment shown in FIG. 4has a three-layer structure. Reference numerals 60, 61, 62 indicatemagnetic material layers forming the free magnetic layer 28, and themagnetic material layer 60 is a diffusion-blocking layer for inhibitingdiffusion of elements with the nonmagnetic material layer 27. Themagnetic material layer 60 is formed of a CoFe alloy, Co, or the like.

The magnetic material layer 62 is formed in contact with the secondantiferromagnetic layer 31. The magnetic material layer 62 is preferablyformed of a CoFe alloy or a CoFeCr alloy, and hence an exchange couplingmagnetic field generated between the magnetic material layer 62 and thesecond antiferromagnetic layer 31 can be increased.

As the combination of materials forming the three-layer structure shownin FIG. 4, for example, a CoFe alloy for the magnetic material layer 60,a NiFe alloy for the magnetic material layer 61, and a CoFe alloy forthe magnetic material layer 62 may be mentioned.

The free magnetic layer 28, which is formed of only magnetic materials,preferably has a thickness of approximately 30 to 40 Å. In addition, thecomposition of the CoFe alloy used for the free magnetic layer 28 is,for example, 90 atomic percent of Co and 10 atomic percent of Fe.

FIG. 5 is a partly enlarged cross-sectional view showing anotherembodiment of the free magnetic layer 28. The free magnetic layer 28shown in FIG. 5 has a so-called artificial ferrimagnetic structure. Bythis structure, the effective magnetic thickness of the free magneticlayer 28 can be decreased without extremely decreasing the physicalthickness thereof, and hence the sensitivity to an external magneticfield can be improved.

Reference numerals 63 and 65 indicate magnetic layers, and referencenumeral 64 indicates a nonmagnetic interlayer. The magnetic layers 63and 65 are formed of a magnetic material such as a NiFe alloy, a CoFealloy, a CoFeNi alloy, Co, or a CoNi alloy. In particular, the magneticlayer 63 and/or the magnetic layer 65 is preferably formed of a CoFeNialloy. As the composition, it is preferable that the content of Fe be 9to 17 atomic percent, the content of Ni be 0.5 to 10 atomic percent, andthe balance be Co.

Accordingly, a coupling magnetic field by the RKKY interaction effectacting between the magnetic layers 63 and 65 can be increased. Inparticular, the spin flop magnetic field (Hsp) can be increased toapproximately 293 (kA/m) or more. Accordingly, the magnetizations of themagnetic layer 63 and the magnetic layer 65 are appropriately placed inan antiparallel state. In addition, when the composition is within theranges described above, the magnetostriction of the free magnetic layer28 can be controlled in the range of from −3×10⁻⁶ to 3×10⁻⁶, and thecoercive force can be decreased to 790 (A/m) or less.

In addition, improvement in soft magnetic characteristics of the freemagnetic layer 28 can be appropriately achieved, and in addition,decreases of the change in resistance (ΔR) and rate of change inresistance (ΔR/R) caused by the diffusion of Ni with the nonmagneticmaterial layer 27 can appropriately be suppressed.

The nonmagnetic interlayer 64 is preferably formed of at least oneselected from the group consisting of Ru, Rh, Ir, Cr, Re, and Cu.

The thicknesses of the magnetic layer 63, the nonmagnetic interlayer 64,and the magnetic layer 65 are, for example, approximately 35, 9, and 15Å, respectively.

When the free magnetic layer 28 is formed having an artificialferrimagnetic structure, as shown in FIG. 8, the magnetic layer 65 maybe totally removed at the central portion D so that the nonmagneticinterlayer 64 is exposed between the second antiferromagnetic layers 31.Accordingly, the free magnetic layer 28 at the central portion D has notan artificial ferrimagnetic structure and serves as a free magneticlayer composed of only general magnetic layers. In addition, since thefree magnetic layer 28 has artificial ferrimagnetic structures at thetwo side portions C, unidirectional bias magnetic fields can beincreased, the magnetizations of the free magnetic layer 28 at the twoside portions C can be more reliably fixed in the track width direction,and hence the generation of side reading can be prevented.

In addition, between the magnetic layer 63 and the nonmagnetic materiallayer 27, a diffusion-blocking layer formed of a CoFe alloy or Co may beprovided. Furthermore, between the magnetic layer 65 and the secondantiferromagnetic layer 31, a magnetic layer formed of a CoFe alloy maybe provided.

In the case described above, when the magnetic layer 63 and/or themagnetic layer 65 is formed of a CoFeNi alloy, it is preferable that thecomposition ratio of Fe in the CoFeNi alloy be from 7 to 15 atomicpercent, the ratio of the Ni be from 5 to 15 atomic percent, and thebalance be Co.

Accordingly, an exchange coupling magnetic field by the RKKY interactioneffect generated between the magnetic layers 63 and 65 can be increased.In particular, the spin flop magnetic field (Hsp) can be increased toapproximately 293 (kA/m). Accordingly, the magnetizations of themagnetic layer 63 and the magnetic layer 65 can be appropriately placedin an antiparallel state.

In addition, when the composition is within the ranges described above,the magnetostriction of the free magnetic layer 28 can be controlled inthe range of from −3×10⁻⁶ to 3×10⁻⁶, and the coercive force can bedecreased to 790 (A/m) or less. Furthermore, the soft magneticcharacteristics of the free magnetic layer 28 can also be improved.

FIG. 6 is a partly enlarged cross-sectional view of another embodimentof the free magnetic layer 28 of the present invention. In the freemagnetic layer 28 shown in FIG. 6, a specular film 67 is providedbetween the magnetic layers 66 and 68. In the specular film 67, defects(pinholes) G may be formed as shown in FIG. 6. In addition, in theembodiment shown in FIG. 6, the magnetic layers 66 and 68 provided withthe specular film (mirror reflection layer) 67 therebetween aremagnetized in the same direction.

The magnetic layers 66 and 68 are formed of a magnetic material, such asa NiFe alloy, a CoFe alloy, a CoFeNi alloy, Co, or a CoNi alloy.

When the specular film 67 is formed in the free magnetic layer 28, aconduction electron (such as up-spin electron) that reaches the specularfilm 67 is specularly reflected while maintaining the spin state(energy, quantum state, and the like). The up-spin electron thusspecularly reflected changes the traveling direction thereof and canpass through the free magnetic layer.

Accordingly, in the present invention, by providing the specular film67, a mean free path λ+ of the up-spin electron can be increased ascompared to that in the past, the difference between the mean free pathλ+ of the up-spin conduction electron and a mean free path λ− of adown-spin conduction electron can be increased thereby, and as a result,the reproduction output can be improved in addition to the improvementof the rate of change in resistance (ΔR/R).

The formation of the specular film 67 is performed, for example, byforming the magnetic layer 66 through the steps described above followedby oxidation thereof. This oxidized layer may be used as the specularfilm 67. Subsequently, the magnetic layer 68 is formed on the specularfilm 67.

As a material for the specular film 67, for example, there may bementioned an oxide, such as Fe—O, Ni—O, Co—O, Co—Fe—O, Co—Fe—Ni—O, Al—O,Al—Q—O (Q is at least one selected from the group consisting of B, Si,N, Ti, V, Cr, Mn, Fe, Co, and Ni), or R—O (R is at least one selectedfrom the group consisting of Cu, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W);a nitride such as Al—N, Al—Q—N (Q is at least one selected from thegroup consisting of B, Si, O, Ti, V, Cr, Mn, Fe, Co, and Ni), or R—N (Ris at least one selected from the group consisting of Ti, V, Cr, Zr, Nb,Mo, Hf, Ta, and W); or a half-metal whistler alloy.

FIG. 7 is a partly enlarged cross-sectional view of another embodimentof the free magnetic layer 28 of the present invention.

In the free magnetic layer 28 shown in FIG. 7, a back layer 71 is formedbetween the magnetic layer 69 and the second antiferromagnetic layer 31.The back layer 71 is formed, for example, of Cu, Au, Cr, or Ru. Themagnetic layer 69 is formed of a magnetic material such as a NiFe alloy,a CoFe alloy, a CoFeNi alloy, Co, or CoNi alloy.

By providing the back layer 71, the mean free path of an up-spinconduction electron, which contributes to the magnetoresistive effect,is increased, and a high rate of change in resistance can be obtained ina spin-valve type magnetic sensor by a so-called spin filter effect,thereby achieving higher recording density. In addition, since the backlayer 71 serves to allow exchange coupling to pass therethrough,although being slightly decreased, the exchange coupling magnetic fieldbetween the second antiferromagnetic layer 31 and the magnetic layer 69can be maintained at a satisfactory level.

FIGS. 10 to 16 are views showing steps of a method for manufacturing themagnetic sensor shown in FIG. 1. FIGS. 10 to 16 are partlycross-sectional views of the sensor viewed from an opposing face sideopposing a recording medium.

In the step shown in FIG. 10, on the substrate 20, the seed layer 21,the first antiferromagnetic layer 22, the fixed magnetic layer 23, thenonmagnetic material layer 27, the free magnetic layer 28, a solidsecond antiferromagnetic film 31 b, and the nonmagnetic layer 41 aresequentially formed. Film formation is performed by sputtering or vapordeposition. The fixed magnetic layer 23 shown in FIG. 10 has anartificial ferrimagnetic structure composed of the magnetic layers 24and 26, which are formed of a CoFe alloy or the like, and thenonmagnetic interlayer 25 which is formed of Ru or the like and isprovided therebetween. The free magnetic layer 28 has a laminatestructure composed of the diffusion-blocking layer 29 formed of a CoFealloy or the like and the magnetic material layer 30 formed of a NiFealloy or the like.

In the present invention, the first antiferromagnetic layer 22 and thesolid second antiferromagnetic film 31 b are preferably formed of a PtMnalloy, an X—Mn alloy (X is at least one element selected from the groupconsisting of Pd, Ir, Rh, Ru, Os, Ni, and Fe), or a Pt—Mn—X′ alloy (X′is at least one element selected from the group consisting of Pd, Ir,Rh, Ru, Au, Ag, Os, Cr, Ni, Ar, Ne, Xe, and Kr).

In addition, in the alloys represented by PtMn and X—Mn, the Pt or X ispreferably in the range of from 37 to 63 atomic percent. In the alloysrepresented by PtMn and X—Mn, the Pt or X is more preferably in therange of from 47 to 57 atomic percent.

In the alloy represented by Pt—Mn—X′, the X′+Pt is preferably in therange of from 37 to 63 atomic percent. In the alloy represented byPt—Mn—X′ alloy, the X′+Pt is more preferably in the range of from 47 to57 atomic percent. Furthermore, in the alloy represented by Pt—Mn—X′,the X′ is preferably in the range of from 0.2 to 10 atomic percent.However, when the X′ is at least one selected from the group consistingof Pd, Ir, Rh, Ru, Os, Ni, and Fe, the X′ is more preferably in therange of from 0.2 to 40 atomic percent.

In the present invention, the thickness of the first antiferromagneticlayer 22 is preferably set in the range of from 80 to 300 Å. By formingthe first antiferromagnetic layer 22 having a large thickness asdescribed above, a strong exchange coupling magnetic field can begenerated between the first antiferromagnetic layer 22 and the fixedmagnetic layer 23 by annealing in a magnetic field. In particular, anexchange coupling magnetic field of 48 kA/m or more such as more than 64kA/m can be generated.

The thickness of the solid second antiferromagnetic film 31 b ispreferably in the range of from 20 to 50 Å, and more preferably in therange of from 30 to 40 Å.

When the thickness of the solid second antiferromagnetic film 31 bdecreases to a relatively small thickness of 50 Å or less as describedabove, the film has non-antiferromagnetic characteristics. Accordingly,even when the following first annealing in a magnetic field isperformed, the solid second antiferromagnetic film 31 b is unlikely tobe transformed to a film with a regular lattice, the exchange couplingmagnetic field between the solid second antiferromagnetic film 31 b andthe free magnetic layer 28 is not generated or is very weak, and as aresult, in a manner different from that of the fixed magnetic layer 23,the magnetization of the free magnetic layer 28 is not tightly fixed.

The reason the thickness of the solid second antiferromagnetic film 31 bis set to 20 Å or more and preferably set to 30 Å or more is that whenthe thickness thereof is smaller than that as described above, althougha solid second antiferromagnetic film 31 c is formed on the solid secondantiferromagnetic film 31 b in a subsequent step, a solid secondantiferromagnetic film 31 formed of the solid second antiferromagneticfilms 31 b and 31 c is unlikely to have antiferromagneticcharacteristics, and as a result, an appropriately strong exchangecoupling magnetic field is not generated between the solid secondantiferromagnetic film 31 and the free magnetic layer 28.

In addition, as in the step shown in FIG. 10, when the nonmagnetic layer41 is formed on the solid second antiferromagnetic film 31 b, even whenthe laminate shown in FIG. 10 is exposed to the air, the solid secondantiferromagnetic film 31 b is appropriately prevented from beingoxidized.

The nonmagnetic layer 41 is preferably a dense layer unlikely to beoxidized although being exposed to the air. In addition, even whenelements forming the nonmagnetic layer 41 intrude into the solid secondantiferromagnetic film 31 b by thermal diffusion or the like, theelements preferably have properties that will not degrade the propertiesthereof as the antiferromagnetic film.

In the present invention, the nonmagnetic layer 41 is preferably formedof at least one noble metal selected from the group consisting of Ru,Re, Pd, Os, Ir, Pt, Au, and Rh.

The nonmagnetic layer 41 formed of a noble metal such as Ru is a denselayer unlikely to be oxidized even when being exposed to the air. Hence,even when the thickness of the nonmagnetic layer 41 is decreased, thesolid second antiferromagnetic film 31 b is appropriately prevented frombeing oxidized when exposed to the air.

In the present invention, the nonmagnetic layer 41 preferably has athickness of 3 to 10 Å. Even when the nonmagnetic layer 41 has a smallthickness as described above, the solid second antiferromagnetic film 31b can be appropriately prevented from being oxidized when exposed to theair.

In the present invention, since the nonmagnetic layer 41 is formed froma noble metal such as Ru and is formed to have a small thickness ofapproximately 3 to 10 Å, at the stage of excavating the nonmagneticlayer 41 by ion milling, the ion milling can be performed with lowenergy, and ion milling control can be improved as compared to that inthe past.

As shown in FIG. 10, after the individual layers including thenonmagnetic layer 41 are formed on the substrate 20, the first annealingin a magnetic field is performed. While a first magnetic field (Ydirection in the figure) is applied in the direction perpendicular tothe track width Tw (X direction in the figure), heat treatment at afirst heat treatment temperature is performed so that the exchangecoupling magnetic field is generated between the first antiferromagneticlayer 22 and the magnetic layer 24 forming the fixed magnetic layer 23,and as a result, the magnetization of the magnetic layer 24 is fixed inthe Y direction in the figure. The magnetization of the other magneticlayer 26 is fixed in the direction opposite to the Y direction shown inthe figure by exchange coupling due to the RKKY interaction effectacting between the magnetic layer 26 and the magnetic layer 24. In thiscase, for example, the first heat treatment temperature is set to 270°C., and the intensity of the magnetic field is set to 800 kA/m.

In addition, as described above, by this first annealing in a magneticfield, the exchange coupling magnetic field is not generated betweensolid second antiferromagnetic film 31 b and the magnetic material layer30 forming the free magnetic layer 28 or may be very weak even thoughtbeing generated. The reason for this is that since having a small filmthickness of 50 Å or less, the solid second antiferromagnetic film 31 bdoes not have antiferromagnetic characteristics.

It has been construed that when the first annealing in a magnetic fieldis performed, the noble metal such as Ru forming the nonmagnetic layer41 diffuses inside the solid second antiferromagnetic film 31 b.Accordingly, the constituent elements of the solid secondantiferromagnetic film 31 b in the vicinity of the surface after theannealing are primarily the noble metal and elements forming the solidsecond antiferromagnetic film. It has also been construed that the noblemetal that diffused inside the solid second antiferromagnetic film 31 bhas a higher concentration at the front surface side thereof than thatat the rear surface side, and the composition ratio of the noble metalthus diffused gradually decreases from the front surface side of thesolid second antiferromagnetic film 31 b to the rear surface sidethereof. The change in composition described above can be measured by aSIMS analyzer or the like.

The nonmagnetic layer 41 is then removed by ion milling. The reason thenonmagnetic layer 41 is removed in this step is that when the thicknessof the nonmagnetic layer 41 is not decreased as small as possible, anantiferromagnetic interaction effect cannot be generated between thesolid second antiferromagnetic film 31 b and the solid secondantiferromagnetic film 31 c further provided thereon in the followingstep.

In the present invention, the entire nonmagnetic layer 41 may be removedby this ion milling step; however, when having a thickness of 3 Å orless, the nonmagnetic layer 41 may remain. When the thickness of thenonmagnetic layer 41 is decreased to the level as described above, thesolid second antiferromagnetic film 31, the thickness of which isincreased by providing the additional layer in the following step, canbe used as an antiferromagnetic material.

In the ion milling step shown in FIG. 10, low-energy ion milling can beused. The reason for this is that the nonmagnetic layer 41 has a verysmall thickness such as approximately 3 to 10 Å. In addition, in thepresent invention, even when the nonmagnetic layer 41 formed of Ru orthe like has a very small thickness such as approximately 3 to 10 Å, thesolid second antiferromagnetic film 31 b formed thereunder can besufficiently prevented from being oxidized, and the amount of thenonmagnetic layer 41 which is removed can be easily controlled by thelow-energy ion milling.

The step shown in FIG. 11 is then performed. In the step shown in FIG.11, on the solid second antiferromagnetic film 31 b having a smallthickness (or on the nonmagnetic layer 41 when a part thereof remains),the solid second antiferromagnetic film 31 c is additionally providedthereon. These two solid second antiferromagnetic films 31 b and 31 cform the solid second antiferromagnetic film 31 having a largethickness. In this step, the solid second antiferromagnetic film 31 isformed to have a thickness of 80 to 300 Å.

Next, a solid first stop film 33, which is to be formed into the firststop layers 33, is formed on the solid second antiferromagnetic film 31.The solid first stop film 33 is preferably formed of at least oneelement selected from the group consisting of Cr, Ta, V, Nb, Mo, W, Fe,Co, Ni, Pt, and Rh. Alternatively, when the solid first stop film 33 isformed of a Cr layer, since diffusion may occur in some cases betweenthe element forming the first electrode layer 34 and the solid firststop film 33, in order to prevent the diffusion described above, thesolid first stop film 33 may be formed of a Cr layer and a Ta layerprovided in that order from the bottom. In addition, the solid firststop film 33 preferably has a thickness of 30 to 100 Å.

Next, a solid first electrode film 34 s, which is to be formed into thefirst electrode layers 34, is formed on the solid first stop film 33.The solid first electrode film 34 s may be formed of Au or the like andis preferably formed of a material having ductility lower than that forthe solid second electrode film 36 s which is formed in a subsequentstep. Accordingly, the sold first electrode film 34 s is preferablyformed of at least one of Cr, Rh, Ru, Ta, and W, or an alloy of Aucontaining at least one of Pd and Cr. In addition, the solid firstelectrode film 34 s preferably has a thickness of 400 to 1,000 Å.

In the step shown in FIG. 12, on the solid first electrode film 34 s,the mask layers 42 disposed with a predetermined space T5 therebetweenin the track width direction (X direction in the figure) are formed. Themask layers 42 may be formed of a resist material or may also be formedof a metal material. When the metal material is used, it becomespossible to make the mask layers 42 remain on the first electrode layers34 in subsequent steps. In the step shown in FIG. 12, the mask layers 42are formed of a metal material. For example, the mask layers 42 areformed of Cr. In the following step, parts of the solid first electrodefilm 34 s, the solid first stop film 33, and the solid secondantiferromagnetic film 31, which are not covered with the mask layers42, are etched, and the mask layer 42 must remain until at least thisetching is complete. Accordingly, when the mask layers 42 are formed,the thickness and the material thereof must be carefully determined inconsideration of various conditions. For example, when the mask layers42 are formed of Cr, and when the solid first stop film 33 is alsoformed of Cr, the thickness of the mask layer 42 must be larger thanthat of the solid first stop film 33; otherwise, when the solid firststop film 33 is removed by etching, the entire mask layers 42 on thesolid first electrode film 34 s are also removed. In addition, the masklayers 42 are preferably formed of a material having an etching ratelower than that of the solid first electrode film 34 s and that of thesolid second antiferromagnetic film 31 or is preferably formed of amaterial which is not etched by etchant gases used for etching the solidfirst electrode film 34 s and the solid second antiferromagnetic film31.

When the mask layers 42 are formed of a metal material, the filmthickness thereof is preferably in the range of from approximately 100to 500 Å.

Subsequently, the part of the solid first electrode film 34 s (indicatedby dotted lines shown in FIG. 12) is removed by etching. In thisetching, reactive ion etching (RIE) is preferably used. As an etchantgas, for example, a mixture of CF₄ and C₃F₈, Ar and CF₄, or Ar and C₃F₈may be used.

When the part of the solid first electrode film 34 s indicated by thedotted lines is removed, the surface of the solid first stop film 33 isexposed.

In the step shown in FIG. 13, the solid first stop film 33 exposedbetween the mask layers 42 is removed by ion beam etching (IBE) (dottedlines indicate the removed solid first stop film 33), and the solidsecond antiferromagnetic film 31 formed thereunder is partly removed byion beam etching (dotted lines indicate the removed solid secondantiferromagnetic film). As shown in FIG. 13, the connecting layer 31 ehaving a thickness h1 is formed on the central portion D, and thethickness h1 is preferably 50 Å or less, and more preferably 40 Å orless. The reason for this is that when the thickness h1 of theconnecting layer 31 e is large, an exchange coupling magnetic field isalso generated with the free magnetic layer 28 at this position, and asa result, magnetization control of the free magnetic layer 28 cannot beappropriately performed. The amount of the solid secondantiferromagnetic film 31 removed by etching may be controlled using aSIMS analyzer. In addition, the entire connecting layer 31 e at thecentral portion D may be removed so that the surface of the freemagnetic layer 28 is exposed. However, since it is difficult to stopetching at the same time when the entire connecting layer 31 is removed,in the case described above, the free magnetic layer 28 is influenced bythis etching, and hence the connecting layer 31 e having a smallthickness of 50 Å or less is preferably allowed to remain at the centralportion D as shown in FIG. 13.

In addition, when the solid first electrode film 34 s, the solid firststop film 33, and the solid second antiferromagnetic film 31, exposedbetween the mask layers 42, are removed by etching, continuous inclinedor curved surfaces can be formed from the internal end surfaces 34 a ofthe first electrode layers 34 and the internal end surfaces 31 a of thesecond antiferromagnetic layers 31. In addition, as shown in FIG. 13,the mask layers 42 may be allowed to remain slightly on the firstelectrode layers 34.

Next, the step shown in FIG. 14 is performed. In the step shown in FIG.14, on the upper surfaces 42 a of the mask layers 42, the internal endsurfaces 34 a of the first electrode layers 34, the internal endsurfaces 31 a of the second antiferromagnetic layers 31, and the uppersurface 31 d of the connecting layer 31 e at the central portion D, asolid second stop film 35, which is to be formed into the second stoplayers 35, is formed by sputtering. As sputtering, for example, ion beamsputtering, long-throw sputtering, or collimation sputtering may beused. For example, in this step, ion beam sputtering is used. In thisstep, a sputtering angle (inclination from the direction (Z direction inthe figure) perpendicular to the substrate 20) is represented by θ1. InFIG. 14, the sputtering angle θ1 is approximately 45° with respect tothe substrate 20; however, the sputtering angle θ1 may be set moreperpendicular to the substrate 20. When the sputtering angle θ1 isincreased, that is, sputtering is performed in a more inclineddirection, the solid second stop film 35 having a large thickness isformed on the internal end surfaces 34 a of the first electrode layers34 and the internal end surfaces 31 a of the second antiferromagneticlayers 31, and on the other hand, on the upper surfaces 42 a of the masklayers 42 and the upper surface 31 d of the connecting layer 31 e, thesolid second stop film 35 having a small thickness is formed. Inparticular, the thickness of the solid second stop film 35 formed on theupper surface 31 d of the connecting layer 31 e is smaller than thatformed on each of the upper surfaces 42 a of the mask layers 42. This isdue to the shadow effect.

However, the solid second stop film 35 having a predetermined thicknessis preferably formed on the upper surface 31 d of the connecting layer31, and the reason for this is that the solid second stop film 35 onthis position must appropriately serve as a stop layer in a subsequentstep. Accordingly, the sputtering angle θ1 is preferably not so largeand may be perpendicular (Z direction in the figure) to the substrate20.

In the step described above, the solid second stop film 35 is preferablyformed of Cr or at least one element selected from the group consistingof Ta, V, Nb, Mo, W, Fe, Co, Ni, Pt, and Rh. Conductivity of the solidsecond stop film 35 is preferably taken into account in selecting thematerial used. Since part of the solid second stop film 35 remains underthe second electrode layer 36, and sense current flows from the secondelectrode layer 36 to the multilayer film 40, when the solid second stopfilm 35 has electrical insulating properties, the flow of sense currentis inhibited.

Next, the solid second stop film 35 is preferably formed of a materialhaving a lower etching rate than that of the solid second electrode film36 s. Alternatively, the solid second stop film 35 is preferably formedof a material which is not etched with etchant gases used for etchingthe solid second electrode film 36 s. When the solid second electrodefilm 36 s is formed, for example, of Au, an Ar gas or a mixture of an Argas and C₃F₈ is used as an etchant therefor, and when the solid secondstop film 35 is formed of Cr or the like, the etching rate thereof by anAr gas or a mixture of an Ar gas and C₃F₈ can be decreased as comparedto that of the solid second electrode film 36 s.

In the step shown in FIG. 14, the solid second electrode film 36 s isformed on the solid second stop film 35 by sputtering. As sputtering,for example, ion beam sputtering, long-throw sputtering, or collimationsputtering may be used. For example, in this step, ion beam sputteringis used. In this step, a sputtering angle (inclination from thedirection (Z direction in the figure) perpendicular to the substrate 20)is represented by θ2. The sputtering angle θ2 is in the range of fromapproximately 50 to 70°. That is, the sputtering angle θ2 is set largerso that sputtering is performed in a more inclined direction for formingthe solid second electrode film 36 s.

When the sputtering angle θ2 is set larger as described above, a filmthickness T6 of the solid second electrode film 36 s in the track widthdirection (X direction in the figure), which is formed on the internalend surfaces 34 a of the first electrode layers 34 and the internal endsurfaces 31 a of the second antiferromagnetic layers 31 with the solidsecond stop film 35 provided therebetween, is larger than a filmthickness T7 of the solid second electrode film 36 s formed on the uppersurface 31 d of the connecting layer 31 e with the solid second stopfilm 35 provided therebetween and a film thickness T8 of the solidsecond electrode film 36 s formed on the upper surface of the firstelectrode layer 34 with the mask layer 42 and the solid second stop film35 provided therebetween.

As described above, when the film thickness of the solid secondelectrode film 36 s is not adjusted, by ion milling or reactive ionetching (RIE), the solid second electrode film 36 s formed on theinternal end surfaces 34 a and 31 a of the first electrode layers 34 andthe second antiferromagnetic layers 31 is entirely removed. Even whenthe solid second electrode is allowed to remain, the thickness of thesolid second electrode film 36 s becomes very small, and as a result,the electrode layers having an appropriate overlap structure cannot beformed.

The film thickness T7 of the solid second electrode film 36 s formed onthe upper surface 31 d of the connecting layer 31 e at the centralportion D is small as compared to the film thickness T8 of that abovethe first electrode layer 34. The reason for this is that since the tallfirst electrode layers 34 are present at the two sides in the trackwidth direction of the upper surface 31 d of the connecting layer 31 e,shadows are likely to be formed thereon by the presence of the firstelectrode layers 34 described above when sputtering is performed. Thisis a so-called shadow effect.

In this step, the solid second electrode film 36 s is easily formed sothat the thicknesses T6 on the left side shown in FIG. 14 and that onthe right side are equivalent to each other. That is, in the past, whenthe electrode layers are formed, mask alignment must be performed twice,and hence alignment deviation has been liable to occur when maskalignment is performed for forming the electrodes. However, according tothe present invention, when the solid second electrode film 36 s isformed, mask alignment performed in the past is not necessary. Hence, inthe step shown in FIG. 14 according to the present invention, on theinternal end surfaces 34 a of the first electrode layers 34 and theinternal end surfaces 31 a of the second antiferromagnetic layers 31,the solid second electrode film 36 s is easily formed so that thethicknesses T6 shown in the figure on the left side and that on theright side are equivalent to each other.

Next, as shown by arrows in FIG. 15, ion milling is performed with anangle perpendicular (parallel to Z direction in the figure) orapproximately perpendicular (0 to 20° inclined from the directionperpendicular to the individual surfaces of the layers forming themultilayer film) to the substrate 20. Alternatively, anisotropic etchingis performed by reactive ion etching. In this step, until the solidsecond electrode film 36 s formed at center E on the upper surface 31 dof the connecting layer 31 e is appropriately removed, ion milling orRIE is continued. By this ion milling or RIE, although parts of thesolid second electrode film 36 s formed above the upper surfaces 34 b ofthe first electrode layers 34 are also removed, the solid secondelectrode film 36 s having a small thickness is still likely to remainthereon. However, since the solid second electrode film 36 s formedabove the upper surfaces of the first electrode layers 34 is easilyremoved by ion milling as compared to that formed at the center E on theupper surface 31 d of the connecting layer 31 e, depending on thethickness of the solid second electrode film 36 s formed by deposition,before the solid second electrode film 36 s formed at the center E onthe upper surface 31 d of the connecting layer 31 e is entirely removed,the solid second electrode film 36 s formed above the upper surfaces 34b of the first electrode layers 34 may be entirely removed in somecases.

The solid second electrode film 36 s formed on the internal end surfaces34 a of the first electrode layers 34 and the internal end surfaces 31of the second antiferromagnetic layers 31 is also slightly removed;however, the thickness thereof is larger than that of the solid secondelectrode film 36 s on the upper surface 31 d of the connecting layer 31e, and in addition, the milling direction of ion milling is inclinedwith respect to the solid second electrode film 36 s formed on theinternal end surfaces 34 a of the first electrode layers 34 and theinternal end surfaces 31 of the second antiferromagnetic layers 31.Accordingly, the solid second electrode film 36 s formed on the internalend surfaces 34 a of the first electrode layers 34 and the internal endsurfaces 31 of the second antiferromagnetic layers 31 is unlikely to beremoved as compared to that formed on the upper surface 31 d of theconnecting layer 31 e, and hence the solid second electrode film 36 shaving an appropriate thickness T9 is formed on the internal endsurfaces 34 a and 31 a of the first electrode layers 34 and the secondantiferromagnetic layers 31.

As shown in FIG. 15, the solid second stop film 35 is exposed at thecenter E at which the solid second electrode film 36 s is removed. Thesolid second stop film 35 is formed, for example, of a material havingan etching rate lower than that of the solid second electrode film 36 sdescribed above. Accordingly, overetching is performed for entirelyremoving the solid second electrode film 36 s on the center E, the solidsecond stop film 35 appropriately protects the layer provided thereunderfrom the etching.

In the step of ion milling or RIE shown in FIG. 15, the solid secondelectrode film 36 s formed on the internal end surfaces 34 a of thefirst electrode layers 34 and the internal end surfaces 31 a of thesecond antiferromagnetic layers 31 is evenly removed so that thethickness thereof at the left side and that at the right side areequivalent to each other. Hence, after the ion milling or RIE, the filmthicknesses T9 of the solid second electrode film 36 s, shown in FIG.15, at the left side and the right side are equivalent to each other.

In addition, as shown in FIG. 15, when the solid second electrode film36 s at the center E is removed, parts of the solid second electrodefilm 36 s thus formed extend along the internal end surfaces 34 a and 31a to the two sides of the central portion D and serve as current pathsthrough which sense current flows to the multilayer film 40. Inaddition, the width dimension in the track width direction (X directionin the figure) between the bottom portions of the parts of the solidsecond electrode film 36 s is defined as the track width Tw.

By the step shown in FIG. 15, manufacturing of the magnetic sensor maybe completed; however, as described with reference to FIG. 9, when thisstep is completed, since the solid second electrode film 36 s stillremains on the insulating layer 70 widely extending at the rear side inthe height direction, it is preferable that this solid second electrodefilm 36 s be appropriately removed.

When the step shown in FIG. 15 is completed, the solid second stop film35 is exposed at the center E between the parts of the solid secondelectrode film 36 s. As described above, this solid second stop film 35is formed, for example, of a material having an etching rate lower thanthat of the solid second electrode film 36 s. Accordingly, when thesolid second electrode film 36 s remaining on the insulating layer 70shown in FIG. 9 is removed by etching, the solid second stop film 35 isinfluenced by this etching; however, when being formed so as to have anappropriate thickness, the entire solid second stop film 35 is notremoved before the solid second electrode film 36 s remaining on theinsulating layer 70 is totally removed.

In the step shown in FIG. 16, ion milling is further performed, andhence the solid second electrode film 36 s remaining on the insulatinglayer 70 is removed. In this step, the solid second electrode film 36 sformed above the upper surfaces 34 b of the first electrode layers 34with the mask layers 42 and the second stop layers 35 providedtherebetween is also removed. When the solid second electrode film 36 sremaining on the insulating layer 70 is entirely removed, the ionmilling is stopped.

In FIG. 16, the solid second stop film 35 does not remain on the centerE at all; however, as shown by a dotted line, part of the solid secondstop film 35 may remain. In addition, on the first electrode layers 34,none of the mask layers 42 and the second stop layers 35 remain;however, as above, parts of them may also remain (this is notillustrated by a dotted line).

In addition, since the milling angle used in the milling shown in FIG.16 is close to perpendicular to the substrate 20 (shown by the arrows),the solid second electrode film 36 s formed on the internal end surfaces34 a of the first electrode layers 34 and the internal end surfaces 31of the second antiferromagnetic layers 31 is not subject to theinfluence of this ion milling; however, the solid second electrode film36 s is slightly removed to have a thickness T4, and the thicknessesthereof at the left and the right sides are still equivalent to eachother. This thickness T4 is the overlap length on the multilayer film40, and in the present invention, the thickness T4 described above ispreferably in the range of from 50 to 500 Å. When the milling shown inFIG. 16 is completed, the second electrode layers 36 are formed from thesolid second electrode film 36 s.

Next, second annealing in a magnetic field is performed. Themagnetization direction in this step is the track width direction (Xdirection in the figure). In this second annealing in a magnetic field,a second magnetic field for application is set smaller than an exchangeanisotropic magnetic field of the first antiferromagnetic layer 22, andin addition, the heat treatment temperature is set lower than theblocking temperature of the first antiferromagnetic layer 22. The secondmagnetic field is preferably set stronger than the saturated magneticfield of the free magnetic layer 28 and the antimagnetic field thereof.Accordingly, while the direction of the exchange anisotropic magneticfield of the first antiferromagnetic layer 22 is set in the heightdirection (Y direction in the figure), the direction of the exchangeanisotropic magnetic field of the second antiferromagnetic layer 31 canbe set in the track width direction (X direction in the figure). In thisstep, for example, the second heat treatment temperature is set to 250°C., and the intensity of the magnetic field is set to 24 kA/m.

By the second annealing in a magnetic field described above,transformation to regular lattices occurs appropriately in the secondantiferromagnetic layers 31 at the two side portions C, and exchangecoupling magnetic fields having an appropriate intensity are generatedbetween the antiferromagnetic layers 31 at the two end portions C andthe respective two end portions C of the free magnetic layer 28.Accordingly, the magnetizations of the free magnetic layer 28 at the twoside portions C are fixed in the track width direction (X direction inthe figure).

The second annealing in a magnetic field may be performed, for example,after the solid second stop film 35 is formed in the step shown in FIG.14, or after the solid second electrode film 36 s is formed.

Subsequently, as shown in FIG. 1, a Ta layer is continuously formed onthe upper surfaces 34 b of the first electrode layers 34, the secondelectrode layers 36, the second antiferromagnetic layers 31, and theconnecting layer 31 e, and is then oxidized, thereby forming an oxideused as the protective layer 37.

In the method for manufacturing the magnetic sensor shown in FIG. 2,after the step shown in FIG. 15, the magnetic sensor is covered, forexample, with a resist layer, the insulating layer 70 shown in FIG. 9 isheld without being covered with the resist layer, only the solid secondelectrode film 36 s remaining on this insulating layer 70 is removed byion milling, and subsequently, the resist layer is removed, whereby themagnetic sensor according to the embodiment shown in FIG. 2 is formed.

In the method for manufacturing the magnetic sensor, according to thepresent invention, it is not necessary to perform mask alignment twice,and the first electrode layers 34 and the second electrode layers 36 canbe separately formed. In the step shown in FIG. 12, mask alignment isperformed once, and the first electrode layers 34 each having apredetermined shape are formed on the second antiferromagnetic layers 31at the two side portions C; however, when the second electrode layers 36are formed in the steps shown in FIGS. 14 to 16, mask alignment is notnecessary, and by performing only sputtering for film formation and ionmilling or RIE, the second electrode layers 36 can be formed so that thefilm thicknesses thereof at the left side and the right side areequivalent to each other. Hence, an overlap structure in which thethicknesses of electrodes at the left and the right side are equivalentto each other can be formed precisely.

The reason for this is that the first electrode layers 34 and the secondelectrode layers 36 are formed separately. When these electrode layersare not formed separately, as is the case in the past, mask alignmentmust be performed twice, the alignment accuracy is degraded, and as aresult, an overlap structure in which the thicknesses of electrodes atthe left and the right side are equivalent to each other cannot beformed. In addition, in the present invention, assuming that the firstelectrode layers 34 are not formed, on the second antiferromagneticlayers 31, very thin second electrode layers 36 are formed, or thesecond electrode layers 36 are not formed at all. In this case, ascurrent paths which conduct sense current to the second electrode layers36 which overlap the multilayer film 40, the second antiferromagneticlayers 31 must be used, and as a result, the object to solve the problemin that element resistance is increased cannot be achieved.

That is, in the present invention, the first electrode layers 34 havinga predetermined thickness, which are used as current paths for thesecond electrode layers 36, are formed on the second antiferromagneticlayers 31, and in a step separate from that for the first electrodelayers 34, the second electrode layers 36 are formed so as to justoverlap the multilayer film 40 (that is, the formation of the secondelectrode layers 36 on the second antiferromagnetic layers 31 is not theprimary object). Accordingly, mask alignment is not necessary when thesecond electrode layers 36 are formed, and the second electrode layers36 can be formed so that the thicknesses thereof at the left and theright side are equivalent to each other.

Next, in addition to the method shown in FIGS. 10 to 13, theantiferromagnetic layers 31 and the first electrode layers 34 can alsobe formed by the following method.

In a step shown in FIG. 17 (a partly cross-sectional view of a magneticsensor in a manufacturing step, the sensor being viewed from an opposingface opposing a recording medium), on the substrate 20, the seed layer21, the first antiferromagnetic layer 22, and the fixed magnetic layer23 having an artificial ferrimagnetic structure, the nonmagneticmaterial layer 27, the free magnetic layer 28, and the nonmagnetic layer41 are sequentially formed. The film formation may be performed bysputtering or vapor deposition.

The individual layers are equivalent to those described with referenceto FIG. 10. The nonmagnetic layer 41 is preferably a dense layer that isnot subject to oxidation when being exposed to the air. In addition,even when elements constituting the nonmagnetic layer 41 intrude intothe ferromagnetic layer 51, the second antiferromagnetic layers 31, andthe free magnetic layer 28 by thermal diffusion or the like, theelements preferably have properties that will not degrade the propertiesthereof as the antiferromagnetic layer and the ferromagnetic layer.

In the present invention, the nonmagnetic layer 41 is preferably formedof at least one noble metal selected from the group consisting of Ru,Re, Pd, Os, Ir, Pt, Au, and Rh.

The nonmagnetic layer 41 formed of a noble metal such as Ru is a denselayer that is unlikely to be oxidized even when being exposed to theair. Hence, even when the thickness of the nonmagnetic layer 41 isdecreased, the free magnetic layer 28 is appropriately prevented frombeing oxidized.

In the present invention, the nonmagnetic layer 41 preferably has athickness of 3 to 10 Å. Even when the nonmagnetic layer 41 has a smallthickness as described above, the free magnetic layer 28 can beappropriately prevented from being oxidized.

In the present invention, since the nonmagnetic layer 41 is formed of anoble metal such as Ru having a small thickness of approximately 3 to 10Å, at the stage of excavating the nonmagnetic layer 41 by ion milling,the ion milling can be performed with low energy, and ion millingcontrol can be improved as compared to that in the past.

As shown in FIG. 17, after the individual layers including thenonmagnetic layer 41 are formed on the substrate 20, a first annealingin a magnetic field is performed. While a first magnetic field (Ydirection in the figure) is applied in the direction perpendicular tothe track width Tw (X direction in the figure), heat treatment at afirst heat treatment temperature is performed so that an exchangecoupling magnetic field between the first antiferromagnetic layer 22 andthe magnetic layer 24 forming the fixed magnetic layer 23 is generated,and the magnetization of the magnetic layer 24 is fixed in the Ydirection in the figure. The magnetization of the other magnetic layer26 is fixed in the direction opposite to the Y direction shown in thefigure by exchange coupling of the RKKY interaction effect actingbetween the magnetic layers 24 and 26. For example, the first heattreatment temperature is set to 270° C., and the intensity of themagnetic field is set to 800 kA/m.

Next, as shown in FIG. 18, a resist layer 50 for lift-off purpose isformed on the nonmagnetic layer 41. The width dimension of the resistlayer 50 at the bottom surface in the track width direction (X directionin the figure) is approximately equivalent to that of the centralportion D of the multilayer film 40.

Two side portions 41 a of the nonmagnetic layer 41, which are notcovered with the resist layer 50, are removed by ion milling. The reasonthe nonmagnetic layer 41 is removed in this step is that when thethicknesses thereof at the two side portions are not decreased as smallas possible, appropriate interlayer coupling between the ferromagneticlayer 51 to be formed in the following step and the free magnetic layer28 cannot be obtained.

In the present invention, in this ion milling step, the entirenonmagnetic layer 41 may be removed; however, when the thickness thereofis merely 3 Å or less, the nonmagnetic layer 41 may remain. When thenonmagnetic layer 41 is processed to have a small thickness as describedabove, appropriate interlayer coupling between the ferromagnetic layer51 to be formed in the following step and the free magnetic layer 28 canbe generated, and hence the magnetization control of the free magneticlayer 28 can be appropriately performed.

In the ion milling step shown in FIG. 18, low-energy ion milling isused. The reason for this is that the nonmagnetic layer 41 has a verysmall thickness of approximately 3 to 10 Å. In the present invention,even when the nonmagnetic layer 41 formed of Ru or the like has a verysmall thickness of approximately 3 to 10 Å, the free magnetic layer 28formed thereunder can be sufficiently prevented from being oxidized, andthe amount of the nonmagnetic layer 41 which is milled by the low-energyion milling can be easily controlled.

After the two side portions 41 a of the nonmagnetic layer 41 are removedby ion milling, on the two side portions C of the free magnetic layer 28(or on the nonmagnetic layer 41 when remaining), the ferromagneticlayers 51, the second antiferromagnetic layers 31, and the firstelectrode layers 34 are sequentially formed by sputtering. The“sequential film formation by sputtering” means that the films areformed by sputtering while continuously maintaining an evacuated state.By sequentially forming the ferromagnetic layers 51 and the secondantiferromagnetic layers 31 by sputtering, exchange coupling magneticfields having an appropriate intensity can be generated therebetween,and by the interlayer coupling between the ferromagnetic layers 51 andthe free magnetic layer 28, the magnetizations of the free magneticlayer 28 at the two side portions C can be fixed in the X direction inthe figure. Subsequently, the resist layer 50 shown in FIG. 19 isremoved. Next, by performing the steps shown in FIGS. 14 to 16, thesecond electrode layers 36 are each continuously formed on the internalend surface 34 a of the first electrode layer 34, the internal endsurface 31 a of the second antiferromagnetic layer 31, and part of theupper surface of the multilayer film 40. Hence, the magnetic sensorshown in FIG. 3 can be manufactured.

In addition to the two manufacturing methods including the step offorming the first electrode layers 34 and the preceding steps describedabove, another method may be used. Depending on a manufacturing methodincluding a step of forming the first electrode layers 34 and thepreceding steps, the embodiment of the magnetic sensor may vary to someextent; however, although the variation is present, when the secondelectrode layers 36 are each continuously formed on the internal endsurface 34 a of the first electrode layer 34, the internal end surface31 a of the second antiferromagnetic layer 31, and a part of the uppersurface of the multilayer film 40, the magnetic sensor is within therange of the present invention.

FIG. 20 is a partly cross-sectional view of a magnetic sensor viewedfrom an opposing face opposing a recording medium, the magnetic sensorhaving longitudinal bias means different from that of each of themagnetic sensors shown in FIGS. 1 to 3, and 8.

In the embodiment shown in FIG. 20, on the substrate 20, the seed layer21, the first antiferromagnetic layer 22, the fixed magnetic layer 23having an artificial ferrimagnetic structure, the nonmagnetic materiallayer 27, the free magnetic layer 28, and a protective layer 52 areprovided in that order, thereby forming a multilayer film 55. Materialsand the like for the individual layers are equivalent to those describedwith reference to FIG. 1, and descriptions thereof are omitted. Theprotective layer 52 is formed of Ta or the like.

In the embodiment shown in FIG. 20, from the lower side to the upperside (Z direction in the figure), the distance between two end surfaces55 a in the track width direction (X direction in the figure) of themultilayer film 55 is gradually decreased so that inclined or curvedsurfaces are formed.

As shown in FIG. 20, at two sides of the multilayer film 55 in the trackwidth direction (X direction in the figure), hard bias layers 53 areformed. The hard bias layers 53 are each a permanent magnet film formed,for example, of a CoPt alloy or a CoPtCr alloy, and the magnetization ofthe free magnetic layer 28 is aligned in the track width direction (Xdirection in the figure) by a longitudinal bias magnetic field from thehard bias layers 53.

On the hard bias layers 53, first electrode layers 54 are formed. Thefirst electrode layer 54 is preferably formed of an alloy of Aucontaining at least one of Pd and Cr, or at least one of Cr, Rh, Ru, Ta,and W. Accordingly, the ductility of the first electrode layer 54 can bedecreased, and when the opposing face of the magnetic sensor, opposing arecording medium, is polished when a slider is formed, short circuiting,which is caused by the generation of smearing in the first electrodelayer 54, between the first electrode layer 54 and an upper shield layeror a lower shield layer can be appropriately prevented.

In the embodiment shown in FIG. 20, the internal end surfaces 54 a ofthe first electrode layers 54 are located above the upper surface of themultilayer film 55, and the second electrode layers 36 are formed on therespective internal end surfaces 54 a of the first electrode layers 54with the stop layers (equivalent to the second stop layers in FIG. 1) 35provided therebetween. The second electrode layers 36 are formedextending to the upper surface of the multilayer film 55, and thedistance between the second electrode layers 36 in the track widthdirection (X direction in the figure) defines the track width Tw.

In the embodiment shown in FIG. 20, after the first electrode layers 54are formed, by using the steps shown in FIGS. 14 to 16, the secondelectrode layers 36 can be continuously formed on the respectiveinternal end surfaces 54 a of the first electrode layers 54 and parts ofthe upper surface of the multilayer film 55.

According to the present invention, the second electrode layers 36provided at two sides in the track width direction, which have thethicknesses equivalent to each other and which overlap the multilayerfilm 55, can be precisely formed. The reason for this is that amanufacturing method in which mask alignment is performed twice forforming the electrode layers is not used, and hence while fulfillingrecent narrower track requirement, the magnetic sensor of the embodimentaccording to the present invention can simultaneously achieve thedecrease in element resistance and the reduction of generation of sidereading.

In addition, the magnetic sensor of the present invention may be used invarious applications such as that used in a magnetic head embedded in ahard disc device.

As has been thus described, in the magnetic sensor of the presentinvention, since the first electrode layers, which are formed on thesecond antiferromagnetic layers, and the second electrode layers, whichare provided on the respective internal end surfaces of the secondantiferromagnetic layers and the first electrode layers and the uppersurface of the multilayer film, are formed separately, it is notnecessary to perform mask alignment twice, and as a result, an overlapstructure in which the second electrodes at the left and the right sidehave the thicknesses equivalent to each other can be precisely formed.

In the present invention, since the firs electrode layers and the secondelectrode layers can be formed separately, different materials may beused therefor, and for example, the first electrode layers may be formedof a nonmagnetic conductive material having ductility lower than thatfor the second electrode layers. Accordingly, in a polishing step ofslider formation, the generation of smearing can be suppressed, and as aresult, a magnetic sensor having superior reproduction characteristicscan be manufactured.

As described above, in the present invention, since the overlapstructure in which the electrodes at the left and the right side havethe thicknesses equivalent to each other can be formed, which issuperior to an overlap structure formed in the past, in particular,while fulfilling the narrower track requirement, the decrease in elementresistance and the reduction of generation of side reading can beeffectively achieved, and in addition, a magnetic sensor having superiorreproduction output can be manufactured.

What is claimed is:
 1. A magnetic sensor having a multilayer film whichincludes a first antiferromagnetic layer, a fixed magnetic layer, anonmagnetic material layer, and a free magnetic layer provided in thatorder from the bottom, the magnetic sensor comprising: secondantiferromagnetic layers which are disposed with a predetermined spaceprovided therebetween in a track width direction and which are providedon an upper surface of the multilayer film; first electrode layersformed on the second antiferromagnetic layers; and second electrodelayers disposed with a predetermined space provided therebetween in thetrack width direction, the second electrode layers being provided one ordirectly on and indirectly above at least internal end surfaces in thetrack width direction of the first electrode layers and the secondantiferromagnetic layers and parts of the upper surface of themultilayer film.
 2. A magnetic sensor according to claim 1, wherein thefirst electrode layers are formed in a step separate from that of thesecond electrode layers.
 3. A magnetic sensor according to claim 1,wherein the first electrode layers are formed of a material differentfrom that of the second electrode layers.
 4. A magnetic sensor accordingto claim 3, wherein the first electrode layers are formed of a materialhaving ductility lower than that of the second electrode layers.
 5. Amagnetic sensor according to claim 4, wherein the first electrode layersare formed of at least one of Cr, Rh, Ru, Ta, and W, or an alloy of Aucontaining at least one of Pd and Cr, and the second electrode layersare formed of at least one of Au, Cu, and Ag.
 6. A magnetic sensoraccording to claim 1, wherein the second electrode layers are formedonly on the internal end surfaces and the parts of the upper surface ofthe multilayer film.
 7. A magnetic sensor according to claim 1, furthercomprising stop layers, wherein the stop layers are provided under thesecond electrode layers.
 8. A magnetic sensor according to claim 7,wherein the stop layers have an etching rate lower than that of thesecond electrode layers.
 9. A magnetic sensor according to claim 7,wherein the stop layers are formed of at least one element selected fromthe group consisting of Ta, Cr, V, Nb, Mo, W, Fe, Co, Ni, Pt, and Rh.10. A magnetic sensor according to claim 7, wherein the stop layers eachhave a laminate structure composed of a Cr layer and a Ta layer providedin that order from the bottom.
 11. A magnetic sensor according to one ofclaims 1 to 10, wherein the internal end surfaces of the secondantiferromagnetic layers and the internal end surfaces of the firstelectrode layers form continuous surfaces.
 12. A method formanufacturing a magnetic sensor, comprising: step (a) of forming amultilayer film including a first antiferromagnetic layer, a fixedmagnetic layer, a nonmagnetic material layer, and a free magnetic layerprovided in that order on a substrate; step (b) of forming secondantiferromagnetic layers, which are disposed on two side portions of themultilayer film in a track width direction, and first electrode layerson the second antiferromagnetic layers; and step (c) of forming secondelectrode layers one of directly on and indirectly above at leastinternal end surfaces in the track width direction or the firstelectrode layers and the second antiferromagnetic layers and parts of anupper surface of the multilayer film, the second electrode layers beingprovided with a predetermined space provided therebetween in the trackwidth direction.
 13. A method for manufacturing a magnetic sensor,comprising: step (a) of forming a multilayer film including a firstantiferromagnetic layer, a fixed magnetic layer, a nonmagnetic materiallayer, and a free magnetic layer provided in that order on a substrate;step (b) of forming second antiferromagnetic layers, which are disposedon two side portions of the multilayer film in a track width direction,and first electrode layers on the second antiferromagnetic layers; step(d) of forming a solid second electrode film on upper surfaces of thefirst electrode layers, internal end surfaces in the track widthdirection or the first electrode layers and the second antiferromagneticlayers, and an upper surface of the multilayer film; and step (e) ofremoving a center part of the solid second electrode film formed on theupper surface of the multilayer film, whereby second electrode layerswith a predetermined space provided therebetween in the track widthdirection are formed on the internal end surfaces and parts of the uppersurface of the multilayer film.
 14. A method for manufacturing amagnetic sensor, according to claim 13, further comprising forming asolid stop film on the upper surfaces of the first electrode layers, theinternal end surfaces in the track width direction of the firstelectrode layers and the second antiferromagnetic layers, and the uppersurface of the multilayer film after step (b) is performed; and afterpart of the solid stop film is exposed by removing the center part ofthe solid second electrode film in step (e), removing the part of thesolid stop film.
 15. A method for manufacturing a magnetic sensor,according to claim 14, wherein the solid stop film is formed of amaterial having an etching rate lower than that of the solid secondelectrode film.
 16. A method for manufacturing a magnetic sensor,according to claim 13, wherein the solid stop film is formed of at leastone element selected from the group consisting of Ta, Cr, V, Nb, Mo, W,Fe, Co, Ni, Pt, and Rh.
 17. A method for manufacturing a magneticsensor, according to claim 14, wherein the solid stop film is formed ofa Cr layer and a Ta layer provided in that order from the bottom.
 18. Amethod for manufacturing a magnetic sensor, according to claim 14,wherein parts of the solid second electrode film formed on the uppersurfaces of the first electrode layers are entirely removed in step (e).19. A method for manufacturing a magnetic sensor, according to claim 13,wherein the solid second electrode film is formed in step (d) bysputtering with a sputtering angle inclined from a directionperpendicular to the substrate, whereby a thickness of the solid secondelectrode film on the internal end surfaces is larger than each of thoseon the upper surface of the multilayer film and on the upper surfaces ofthe first electrode layers.
 20. A method for manufacturing a magneticsensor, according to claim 19, wherein the solid second electrode filmis formed in step (d) so that the thickness thereof on the upper surfaceof the multilayer film is smaller than each of those on the uppersurfaces of the first electrode layers.
 21. A method for manufacturing amagnetic sensor, according to claim 19, wherein, in step (e) of removingthe center part of the solid second electrode film, formed on the uppersurface of the multilayer film, by milling, a milling angle is set closeto perpendicular to the substrate as compared to a sputtering angle usedfor forming the solid second electrode film.
 22. A method formanufacturing a magnetic sensor, according to claim 12, wherein thefirst electrode layers are formed of a nonmagnetic conductive materialdifferent from that of the second electrode layers.
 23. A method formanufacturing a magnetic sensor, according to claim 22, wherein thefirst electrode layers are formed of a material having ductility lowerthan that of the second electrode layers.
 24. A method for manufacturinga magnetic sensor, according to claim 23, wherein the first electrodelayers are formed of at least one of Cr, Rh, Ru, Ta, and W, or an alloyof Au containing at least one of Pd and Cr, and the second electrodelayers are formed of at least one or Au, Cu, and Ag.